浅析TAIC、BIPB在橡胶电缆中的应用

文章介绍橡套电缆绝缘胶和护套胶使用三烯丙基异三聚氰酸酯(TAIC)和双叔丁基过氧化二异丙基苯(BIPB)作硫化体系的原因,以及在橡套电缆中的具体应用实例,并阐述在使用过程中应注意的事项。     

变压器出口短路后电气试验的探讨

在大短路电流作用下,机械损伤的基本形式是变压器绕组变形,它们发展的典型方式是变形引起局部放电,匝、层间短路,整段主绝缘放电或完全击穿导致主绝缘破坏。因此,变压器出口短路后的检测试验一项必要的关系到运行安全的重要工作。     

Dynamics of the shell class of tensegrity structures

A tensegrity structure is a special truss structure in a stable equilibrium, with selected members designated for only tension loading, and the members in tension form a continuous network of cables separated by a set of compressive members. This paper develops an explicit analytical model of the nonlinear dynamics of a large class of tensegrity structures, constructed of rigid rods connected by a continuous network of elastic cables. The kinematics are described by positions and velocities of the ends of the rigid rods, hence, the use of angular velocities of each rod is avoided. The model yields an analytical expression for accelerations of all rods, making the model efficient for simulation, since the update and inversion of a nonlinear mass matrix is not required. The model is intended for shape control and design of deployable structures. Indeed, the explicit analytical expressions are provided herein for the study of stable equilibria and controllability, but the control issues are not treated in this paper.     

EPS板薄抹灰外墙技术在节能住宅的应用

外墙节能是建筑节能的重点项目。随着节能建筑的大量建成及节能要求的进一步提高,外墙外保温技术也不断发展。文章结合工程实例,通过透视EPS板薄抹灰外墙外保温系统技术的应用现状,就如何保证工程质量、围护结构的热工性能和使用功能,实现建筑物的节能目标,介绍一些体会供大家参考。     

论情报的本质

通过实例分析对情报的本质及核心进行探讨。情报的本质为情况之报告,从空间上讲包括他方情况与本方情况,从时间上包括过去的情况、现在的情况以及未来的情况。情报的核心是运用各种手段与方法获取信息,然后运用知识对信息进行分析、理解、汇总,并形成一定形式的报告,报送给相关人员。     

Automatic text structuring and categorization as a first step in summarizing legal cases

The SALOMON system automatically summarizes Belgian criminal cases in order to improve access to the large number of existing and future court decisions. SALOMON extracts relevant text units from the case text to form a case summary. Such a case profile facilitates the rapid determination of the relevance of the case or may be employed in text search. In a first important abstracting step SALOMON performs an initial categorization of legal criminal cases and structures the case text into separate legally relevant and irrelevant components. A text grammar represented as a semantic network is used to automatically determine the category of the case and its components. In this way, we are able to extract from the case general data and to identify text portions relevant for further abstracting. It is argued that prior knowledge of the text structure and its indicative cues may support automatic abstracting. A text grammar is a promising form for representing the knowledge involved.     

Optical fibres for communications

For more than a century telephony has been dependent on elaborate systems of electrically conducting cables. Recently, however, the supremacy of electricity has been challenged by the introduction of glass fibres along which speech is conveyed in the form of modulated optical pulses. This article reviews the technological basis of the method and some typical applications.     

Unbraced cables

For long span cables, either with or without concentrated load, the usual methods of design are found to be inaccurate because they omit the elastic stretch of the cable and they assume an inaccurate shape of the resulting curve. Equations are derived to cover all possible cases, loaded and unloaded cable, based upon assumptions of elastic flexible cables with fixed supports. Equations are also derived showing the variation in several quantities with changes in temperature and movement of supports. Conditions of possible loads and elastic properties of cables are discussed. A bibliography covering major references to the subject is included.     

The impulse strength of solid and gas-filled high voltage cables

A method is presented that allows the computation of the impulse strength of insulating oil and of solid and gas-filled cables. The principle of the calculation is that breakdown is initiated by currents due to an electronic emission from the cathode; in gas-filled cables these currents are increased by means of gaseous ionization in the butt spaces. Approximate equations are deduced and numerical impulse strength values for insulating oil and solid cable computed, resulting in fair agreement with experimental observations. Extending the equations to gas-filled cables, numerical impulse data for varying gas pressure and for varying radial butt-space alignment are evaluated.     

煤炭资源资产负债表编制方法及应用

中国将自然资源资产负债表的编制工作放在了生态文明制度建设的突出位置。煤炭资源是支撑中国国民经济发展的基础能源,编制煤炭资源资产负债表对于加强煤炭资源科学管理以及推进领导干部自然资源资产离任审计工作具有重要的现实意义。本文基于对国外自然资源核算体系以及国内自然资源资产负债表编制方法的梳理,发现现有研究在指导煤炭资源资产负债表编制时存在报表体系不统一、资产估值方法不明确、负债核算内容与方法不完备等不足;进而从中国煤炭资源的赋存特征、勘探开发条件、价值认定与相关能源统计体系入手,厘清了煤炭资源资产负债表编制的基础准备、技术架构以及基本程序,完善了报表体系的核算内容,明确了煤炭资源资产和负债的价值量计算方法,同时设计出煤炭资源资产负债表样表;并以宁夏回族自治区为例,实现了煤炭资源资产负债表编制方法的有效应用。研究成果可为构建中国煤炭资源资产负债表编制体系,在产煤省市乃至全国范围内编制煤炭资源资产负债表提供方法参考。     

天然气门站调压器冰堵故障分析

使用电伴热带缠绕调压单元及信号管加热,用保温材料包裹进行保温来解决调压器冰堵故障问题,调压器安装电伴热保温装置,用220V电压单独供电,电伴热线的功率为30瓦/米,每套电伴热保温装置需电伴热线20米,共360瓦电源。需对调压器信号管、调压单元及前后直管段加电伴热线缠绕同时包裹保温材料,保温材料选用无毒无味的聚氯乙烯(橡塑),每路调压器上电伴热保温装置由独立开关控制,电伴热保温装置的启用应根据环境温度和出站天然气的温度而定。     

Thesaurus-based automatic book indexing

This paper describes a technique for automatic book indexing. The technique requires a dictionary of terms that are to appear in the index, along with all text strings that count as instances of the term. It also requires that the text be in a form suitable for processing by a text formatter. A program searches the text for each occurrence of a term or its associated strings and creates an entry to the index when either is found. The results of the experimental application to a portion of a book text are presented, including measures of precision and recall, with precision giving the ratio of terms correctly assigned in the automatic process to the total assigned, and recall giving the ratio of correct terms automatically assigned to the total number of term assignments according to a human standard. Results indicate that the technique can be applied successfully, especially for texts that employ a technical vocabulary and where there is a premium on indexing exhaustivity.     

Local exponential stabilization via boundary feedback controllers for a class of unstable semi-linear parabolic distributed parameter processes

This paper addresses the problem of local exponential stabilization via boundary feedback controllers for a class of nonlinear distributed parameter processes described by a scalar semi-linear parabolic partial differential equation (PDE). Both the domain-averaged measurement form and the boundary measurement form are considered. For the boundary measurement form, the collocated boundary measurement case and the non-collocated boundary measurement case are studied, respectively. For both domain-averaged measurement case and collocated boundary measurement case, a static output feedback controller is constructed. An observer-based output feedback controller is constructed for the non-collocated boundary measurement case. It is shown by the contraction semigroup theory and the Lyapunov’s direct method that the resulting closed-loop system has a unique classical solution and is locally exponentially stable under sufficient conditions given in term of linear matrix inequalities (LMIs). The estimation of domain of attraction is also discussed for the resulting closed-loop system in this paper. Finally, the effectiveness of the proposed control methods is illustrated by a numerical example.     

火力发电厂基于现场总线的电气控制系统方案探讨

本文介绍了火力发电厂电气控制系统的两种控制模式,即电气现场总线控制系统（EFCS系统）和电气控制管理系统（ECMS系统）,并对这两种控制模式的主要设计模式和监控对象进行了分析比较。ECMS系统不与DCS系统通信,没有减少电气设备进入DCS系统的I/O硬接线。在EFCS系统方案中,小型电动机采用＂全通信＂监控方式进DCS系统,大型电动机及其他电气设备采用＂通信＋硬接线＂监控方式。E-FCS系统与DCS系统进行了网络互联,实现了信息共享,避免了信息重复采集,从而减少了设备和电缆成本及运行维护费用。     

生态等值分析法在草地资源损坏评估中的应用

生态等值分析法（简称HEA法）作为一种对自然资源损坏后做出准确损失效果评估,从而制定恢复实施方案的方法,其特点是原理清晰、参数较少、简单易用、实施便捷,所以在国外应用的领域比较广泛,也得到科学研究领域和社会法制界的认同,但目前在我国应用的较少。文章首先介绍了生态等值分析的概念和基本原理及组成部分,其次对该方法的相关因素进行了梳理和总结,然后以案例的方式分别从开始恢复时间、完成恢复时间和最大恢复服务水平三个角度的数据调整对该方法做了初步的探索应用,最后从实施、技术、经济三个方面对该方法在我国能否实际应用进行了讨论。结果表明,由于在技术条件、产权环境、经济背景等方面国内与国外存在一定的差异,所以HEA法在我国的确认和应用还需要一个探索的过程,并会随着生态补偿问题研究的深入而显得更加迫切。     

论外墙保温节能技术

随着建筑节能和保护大气环境的呼声愈来愈高．外墙保温技术已在我国日益推广应用。外墙保温做法日趋多样化,其技术亦日趋成熟,然而也存在着许多不足。文章意在通过对外墙保温材料性能、做法、优缺点进行阐述、分析、探讨和比较,让业内人士对外墙保温有一个全面的认识并寻求新的发展方向。     

Inter-industry knowledge flows and sectoral networks in the economy of Malaysia

This research probes the configuration of technological systems in terms of inter-sectoral knowledge and intermediate goods exchanges based on a case study of 21 industry sectors in the economy of Malaysia. The case study draws on a network analysis of sectoral knowledge flows survey data and input–output exchange statistics. The results show that knowledge acquisition and dissemination networks are relatively more intra-sector, denser, and centralized than goods exchange networks, which can affect how innovations spread through the economy. Knowledge networks, however, are more likely to form sub-networks with potentially diverse capabilities and influence on the technological system. This adds new information and value for knowledge-based sectoral investment strategies.     

森林资源资产负债表编制基本框架研究

编制自然资源资产负债表是生态文明建设的制度创新之一,森林资源作为自然资源中的重要组成部分,编制资产负债表对于加强森林资源资产监督管理,开展自然资源资产考核具有重要现实意义。本文在回顾国内外森林资源核算研究和自然资源资产负债表编制有关文献研究基础上,借鉴联合国环境经济核算中心框架和前人研究成果,从森林资源实体、具有经营权的森林资源和具有使用权益的森林资源三个层面,结合森林资源管理实际出发,提出了森林资源资产、森林资源负债的概念内涵,对森林资源资产负债表的表式、核算框架进行了探讨分析,设计提出了森林资源存量及变动表、森林资源资产负债表等表式,构建了森林资源资产负债表三层的核算框架。     

Realization and canonical representation of linear systems through I/O maps

In this paper, we use input and output maps to develop simple procedures to obtain minimal realizations for linear continuous-time systems. The procedures developed are numerically efficient and yield explicit formulae for the state-space matrices of the realization in terms of the system parameters, notably the system eigenvalues. Both systems with distinct eigenvalues and repeated eigenvalues are treated. We also present a procedure for transforming a realization obtained through the input or output map to Jordan canonical form. The transformation matrices required to transform the realization to Jordan canonical form are specified entirely in terms of the system eigenvalues. We illustrate the results obtained with several examples.     

Output feedback exponential stabilization of uncertain chained systems

This paper deals with chained form systems with strongly nonlinear disturbances and drift terms. The objective is to design robust nonlinear output feedback laws such that the closed-loop systems are globally exponentially stable. The systematic strategy combines the input-state-scaling technique with the so-called backstepping procedure. A dynamic output feedback controller for general case of uncertain chained system is developed with a filter of observer gain. Furthermore, two special cases are considered which do not use the observer gain filter. In particular, a switching control strategy is employed to get around the smooth stabilization issue (difficulty) associated with nonholonomic systems when the initial state of system is known.